<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>

  <div>
    <button>按钮</button>
  </div>
  <script>
    var btnEl = document.querySelector("button")
    var divEl = document.querySelector("div")


    divEl.onclick = function (event) {
      console.log("divEl:", this)
      console.log("divEl:", event.currentTarget)
      console.log("divEl:", divEl)
      console.log("divEl:", this === divEl)
    }
    
    btnEl.onclick = function () {
      console.log("btnEl:", this)
    }
  </script>
</body>

</html>